Mercaptazole derivatives and their process of preparation



Patented Feb. 22, 1938 MERCAPTAZOLE DERIVATIVES AND, THEIR PROCESS OFPREPARATION Jan Teppema, Cuyahoga Falls, Ohio, assignor to WingfootCorporation, Wilmington,

DeL, a

corporation of Delaware No Drawing. Original application July 7, 1934,

Serial No. 734,232. Divided and this application July 7, 1934, SerialNo. 734,230

23 Claims.

This invention relates to a class of novel reaction products the membersof which, either alone or in conjunction with other substances, areuseful as accelerators of the vulcanization of rubber. It relates, amongother things, to a method of accelerating the processes of vulcanizationby incorporating in the unvulcanized stock certain novel reactionproducts of the kind herein disclosed which not only are comparativelyeasy to prepare but also serve to impart desirable physical propertiesto the vulcanized product. The class of compounds in question are thereaction products of mercaptazoles, such as mercaptothiazoles andmercaptoxazoles, formaldehyde and an ammonium sulphide such as ammoniumhydrogen sulphide, (NI-I4HS) and ammonium sulphide (NH4) 2S. The exactconstitution of these reaction products isas yet not definitely known,consequently, they will be referred to herein as reaction products.

In the preparation of these reaction products a number of variations ofprocedure are possible. Thus, formaldehyde and the desired ammoniumsulphide may be first reacted and this reaction product reacted with themercaptazole. Also, the ammonium sulphide may be reacted with themercaptan and this reaction product reacted with formaldehyde. Anotherprocedure is to first react the mercaptan and formaldehyde and thentreat this reaction product with the ammonium sulphide desired. A stillfurther procedure is to react all three reactants at once.

If a reaction product of formaldehyde and the ammonium sulphide is to beprepared first, it is obtained by simply reacting the two materials.Since the reaction is exothermic, it is generally preferable to reactthe materials in the cold. One method which has been found particularlysuitable is that in which 1000 parts by weight of an approximately 40%solution of ammonium hydrogen sulphide, cooled with approximately 600parts of ice, are mixed with 1620 parts by weight of an aqueous 37%formaldehyde solution. An exothermic reaction takes place with theseparation of a white gummy mass which gradually resinifies. Thismaterial, after being permitted to stand for some time, is ground to afine powder, washed with .water and dried. The reaction proportion offive mols of aldehyde to two mols of the sulphide. Although its exactconstitution is not known, this particular product has been referred toin the 4th edition of Beilstein, volume I, page 563 as penta methylenediamino disulphide. The following equation has been suggested for itsformation:

It will be understood that despite the fact that a name and formula havebeen assigned to this reaction product, there is doubt as to itsconstitution.

While the reaction product of penta methylene diamino disulphide andmercaptazoles have been found to be very effective accelerators, it isto be understood that formaldehyde and ammonia hydrogen sulphide may bereacted in substantially any other proportions. Likewise other ammoniumsulphides such as ammonium sulphide (NH4)2S, may be employed in placeof, or in admixture with, the ammonium hydrogen sulphide.

Example 1 Illustrative of the invention, 32 parts by weight ofl-mercaptobenzothiazole, 32 parts of the penta methylene diaminodisulphide described above and 150 grams of toluol are heated underreflux. At first a, clear solution is obtained, but as the reactionproceeds the reaction product becomes insoluble. After heating underreflux for a period of four hours, the insoluble material is filteredoff and extracted with 3% aqueous ammonia at a temperature in theneighborhood of the boiling point in order to remove any unreactedl-mercaptobenzothiazole. It will be found that the reaction proceedsalmost to completion as two successive extractions yield afteracidification only 1.5 parts of unreacted l-mercaptobenzothiazole. Thereaction product is a grayish white material which melts in theneighborhood of 193-195 degrees C. While the exact formula of. thisreaction product is not known, it has been suggested that the followingequation represents the reaction:

as will be described hereinafter. It is to be understood that it is notnecessary to first grind the reaction product, wash it and dry it beforeits further reaction with the mercaptazole.

In the above example, the formaldehyde and ammonium hydrogen sulphideare reacted in the Alternatively, the reaction product described inExample 1 may be prepared simply by fusing the penta methylene diaminodisulphide and the 1- mercaptobenzothiazole, thus eliminating solventsentirely. In such case 147 grams of the penta proximately 180 degrees C.The product is ex tracted three times with 3% boiling ammonia whereupon260 parts of reaction product remain.

Example 3 Further illustrative of the invention, 835 parts ofl-mercaptobenzothiazole are added to 116 parts of an aqueous solution ofapproximately 44% ammonium hydrogen sulphide. 244 parts of 'a 37%aqueous formaldehyde solution are added slowly, meanwhile agitating themass vigorously and keeping the temperature at approximately 25 degreesC. The mass is then allowed to stand for 16 hours after which it isheated in boiling water. At approximately 80 degrees C. the product isgummy, but on raising the temperature to boiling a white hard product isformed. The product after being extracted with boiling ammonia melts inthe neighborhood of 188-190 degrees C. and is obtained in a yield ofparts.

Example 4 In another variation of the procedure of reacting amercaptazole, formaldehyde and an ammonium sulphide, 132 parts of a38.8% aqueous ammonium hydrogen sulphide solution, 50 parts of 25%aqueous ammonia, 83.5 parts of 1-mercaptobenzothiazole and 200 parts ofice are admixed. To this mixture is added slowly, with stirring, 250parts of a 37% aqueous formaldehyde solution. After all the formaldehydeis added, the temperature is raised to the boiling point. A whitereaction product is obtained, which after grinding and washing with 3%boiling ammonia solution, is obtained in a yield of 114 parts, meltingin the neighborhood of 181 184 degrees C.

Example 5 In still another example of the invention 334 parts ofl-mercaptobenzothiazole are dissolved in a solution of 90 parts ofcaustic soda in 1000 parts of water and to this solution are added 170parts of 37% aqueous formaldehyde solution. The mass is allowed to standfor one hour at 25-30 degrees C. after which the solution is filteredand acidified with a 10% aqueous sulphuric acid solution. A precipitate,consisting essentially of benzothiazyl l-thio methylene hydrin,

forms, and is filtered and washed with water. To the wet cake of thebenzothiazyl l-thio methylene hydrin are added 522 parts of a 39.5%aqueous ammonium hydrogen sulphide solution,

1200parts of ice and 660 parts of a 37% aqueous formaldehyde solution.The mass is allowed to stand for 12 hours, meanwhile being agitated,

and is then boiled for a period of approximately one hour. A whitereaction product, which after being cooled, ground and washed with 2000parts,

It will be understood that the benzothiazyl 1- thio methylene hydrin maybe prepared by other methods, such. as, for example, by suspending 1-mercaptobenzothiazole in alcohol and adding formaldehyde. Thebenzothiazyl l-thio methylene hydrin is very soluble in alcohol and canbe obtained in a pure form by crystallization.

It will be noted that the products obtained in Examples 1 to 5,inclusive, have slightly different melting points although the reactingmaterials are the same. These differences are caused by small amounts ofimpurities which vary according to the method of preparation employed.By dissolving any of the products of Examples 1 to 5 in nitro benzeneand in symmetrical glyceryl-dichlor-hydrin and crystallizing them theycan be obtained in a substantially pure state melting at 223-224 degreesC.

Emample 6 Illustrative of a reaction product employing. ammoniumsulphide (NH4)2S, 168 parts of 1- mercaptobenzothiazole are added to 256parts of a 36% aqueous solution of ammonium sulphide and 400 parts ofice. To this mixture 492 parts of a 37% aqueous formaldehyde solutionare added slowly with agitation. The mixture is allowed to stand forapproximately one hour at a temperature not above 25 degrees C. afterwhich the mass is heated to degrees C. A cream colored reaction productformed which, after being freed from unreacted' l-mercaptobenzothiazoleby extraction with a 2% aqueous sodium hydrom'de solution at 80 degreesC., is obtained in a yield .of 243 grams. The reaction product melts at-122 degrees C.

Example 7 28% aqueous ammonia and 64 parts of 39.5%

aqueous NH-iSH solution. The mixture is agitated and 123 parts of 37%aqueous formaldehyde solution are added slowly thereto. The mass isheated to the boiling point for approximately 15 minutes whereupon awhite reaction product forms. This reaction product, after beingextracted with 500 parts of 3% caustic soda solution at 25 degrees C.and dried, is obtained in the form of. a white powder melting at 211-213 degrees C.

, While the l-mercaptobenzothiazoles have been described in detailherein, it is to be understood that any other mercaptazole may beemployed in the practice of the invention, examples being 5-chlorl-mercaptobenzothiazole, 4-nitro l-mercaptobenzothiazole, 5-nitrol-mercaptobenzothiazole, 4-chlor 5-nitro l-mercaptobenzothiazole,3-phenyl l-mercaptobenzothiazole, 3-methyl 1- mercaptobenzothiazole,5-ethoxy 1-mercaptobenzothiazole, S-methoxy l-mercaptobenzothiazole,l-mercapto benzoxazole, l-mercapto tolyl thiazoles, l-mercaptobenzimidazole, dimethyl 1- mercaptobenzothiazoles, S-phenyl 5-mercapto1- 2-4thi0diazole, l-mercapto naphthothiazoles, 3-p-toly1 5-mercaptol-2-4-thiodiazole and 5- mercapto 1-34-thiodiazoles. Any of thesemercaptazoles may be reacted with formaldehyde and an ammonium sulphideaccording to the different variations of procedure described in thepreceding examples.

,The reaction. products to which the invention relates may be employedas accelerators of vulcanization in substantially any of the ordinaryrubber formulae, one found particularly satisfactory being thefollowing:

This application is a division of application Serial No. '734,232, filedJuly '7, 1934.

It is intended that the patent shall cover, by suitable expression inthe appended claims, whatever features of patentable novelty reside inthe invention.

What I claim is:

1. The l-mercaptobenzothiazole derivative obtainable by heating underreaction conditions approximately equimolar proportions ofi-mercaptobenzothiazole and penta methylene diamino disulphide.

2. The l-mercaptobenzothiazole derivative ob tainable by heating underconditions involving the elimination of water l-mercaptobenzothiazole,formaldehyde and ammonium hydrogen sulphide in the approximateproportions of 1 mol. of thiazole, mols of aldehyde and 2 mols ofammonium hydrogen sulphide.

3. The reaction product obtainable by reacting, with the elimination ofwater, a l-mercaptazole in which the mercapto group is Sl-I,formaldehyde, and an ammonium sulphide.

4. The reaction product obtainable by reacting, with the elimination ofwater, an aryl l-mercaptazole in which the aryl group is selected fromthe benzene and naphthalene series and in which the mercapto group isSH, formaldehyde, and an ammonium sulphide.

5. The reaction product obtainable by reacting, with the elimination ofwater, a l-mercapto arylene thiazole in which the arylene group isselected from the benzene and naphthalene series and in which themercapto group is SH, formaldehyde, and an ammonium sulphide.

6. The reaction product obtainable by reacting, with the elimination ofwater, a l-mercaptobenzothiazole in which the mercapto group is SH,formaldehyde, and an ammonium sulphide.

7. The reaction product obtainable by reacting, with the elimination ofwater, l-mercaptobenzothiazole, formaldehyde, and an ammonium sulphide.

8. The reaction product obtainable by reacting, with the elimination ofwater, l-mercaptobenzothiazole, formaldehyde and ammonium hydrogensulphide.

9. The reaction product obtainable by reacting, with the elimination ofwater, l-mercaptobenzothiazole, formaldehyde and (NI-I4) 28.

10. The reaction product obtainable by reacting, with the elimination ofwater, an arylene thiazyl l-thio methylene hydrin in which the arylenegroup is selected from the benzene and naphthalene series, formaldehyde,and an ammonium sulphide.

11. The reaction product obtainable by reacting a 1-mercaptazole inwhich the mercapto group is SH and pentamethylene diamino disulphide.

12. A l-mercaptazole derivative obtainable by reacting, with theelimination of water, one mol. of a l-mercaptazole in which the mercaptogroup is SH, approximately five mols of formaldehyde, and approximatelytwo mols of an ammonium sulphide.

13. A l-mercaptazole derivative obtainable by reacting, with theelimination of water, one mol. of an aryl l-mercaptazole in which themercapto group is SH, approximately five mols of formaldehyde, andapproximately two mols of an ammonium sulphide.

14. A l-mercaptazole derivative obtainable by reacting, with theelimination of water, one mol. of a l-mercapto arylene thiazole in whichthe arylene group is selected from the benzene and naphthalene seriesand in which the mercapto group is SH, approximately five mols offormaldehyde and approximately two mols of an ammonium sulphide.

15. A l-mercaptobenzothiazole derivative obtainable by reacting, withthe elimination of water, one mol. of a l-mercaptobenzo-thiazole inwhich the mercapto group is -SI-I, approximately five mols offormaldehyde, and approximately two mols of an ammonium sulphide.

16. A 1 mercaptobenzothiazole derivative which is obtainable byreacting, with the elimination of water, one mol. ofl-mercaptobenzothiazole, approximately five mols of formaldehyde, andapproximately two mols of an ammonium sulphide.

17. A l-mercaptobenzothiazole derivative which is obtainable byreacting, with the elimination of water, one mol. ofl-mercaptobenzothiazole, approximately five mols of formaldehyde, andapproximately two mols of an ammonium hydrogen sulphide.

18. A 1 mercaptobenzothiazole derivative which is obtainable byreacting, with the elimination of water, one mol. of1-mercaptobenzothiazole, approximately five mols of formaldehyde andapproximately two mols of (NI-I4) 2S.

19. The process which comprises reacting, with the elimination of water,a l-mercaptazole in which the mercapto group is SH, formaldehyde, and anammonium sulphide.

20. The process which comprises reacting, with the elimination of water,a l-mercaptobenzothiazole in which the mercapto group is SH,formaldehyde, and an ammonium sul-- phide.

21. The process which comprises reacting, with the elimination of water,l-mercaptobenzothiazole, formaldehyde, and an ammonium sulphide.

22. The process which comprises reacting a l-mercaptazole in which themercapto group is SH and pentamethylene diaminodisulphide.

23. The process which comprises reacting, with the elimination of water,an arylene thiazyl l-thio methylene hydrin in which the arylene group isselected from the benzene and naphthalene series, formaldehyde, and anammonium sulphide.

JAN TEPPEMA.

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